Light absorbing particles(LAP, e.g., black carbon, brown carbon, and dust) influence water and energy budgets of the atmosphere and snowpack in multiple ways. In addition to their effects associated with atmospheric...Light absorbing particles(LAP, e.g., black carbon, brown carbon, and dust) influence water and energy budgets of the atmosphere and snowpack in multiple ways. In addition to their effects associated with atmospheric heating by absorption of solar radiation and interactions with clouds, LAP in snow on land and ice can reduce the surface reflectance(a.k.a., surface darkening), which is likely to accelerate the snow aging process and further reduces snow albedo and increases the speed of snowpack melt. LAP in snow and ice(LAPSI) has been identified as one of major forcings affecting climate change, e.g.in the fourth and fifth assessment reports of IPCC. However, the uncertainty level in quantifying this effect remains very high. In this review paper, we document various technical methods of measuring LAPSI and review the progress made in measuring the LAPSI in Arctic, Tibetan Plateau and other mid-latitude regions. We also report the progress in modeling the mass concentrations, albedo reduction, radiative forcing, and climatic and hydrological impact of LAPSI at global and regional scales. Finally we identify some research needs for reducing the uncertainties in the impact of LAPSI on global and regional climate and the hydrological cycle.展开更多
Paralytic shellfi sh poisoning(PSP)microalgae,as one of the harmful algal blooms,causes great damage to the of fshore fi shery,marine culture,and marine ecological environment.At present,there is no technique for real...Paralytic shellfi sh poisoning(PSP)microalgae,as one of the harmful algal blooms,causes great damage to the of fshore fi shery,marine culture,and marine ecological environment.At present,there is no technique for real-time accurate identifi cation of toxic microalgae,by combining three-dimensional fluorescence with machine learning(ML)and deep learning(DL),we developed methods to classify the PSP and non-PSP microalgae.The average classifi cation accuracies of these two methods for microalgae are above 90%,and the accuracies for discriminating 12 microalgae species in PSP and non-PSP microalgae are above 94%.When the emission wavelength is 650-690 nm,the fl uorescence characteristics bands(excitation wavelength)occur dif ferently at 410-480 nm and 500-560 nm for PSP and non-PSP microalgae,respectively.The identification accuracies of ML models(support vector machine(SVM),and k-nearest neighbor rule(k-NN)),and DL model(convolutional neural network(CNN))to PSP microalgae are 96.25%,96.36%,and 95.88%respectively,indicating that ML and DL are suitable for the classifi cation of toxic microalgae.展开更多
Five General Circulation Model(GCM) climate projections under the RCP8.5 emission scenario were used to drive the Variable Infiltration Capacity(VIC) hydrologic model to investigate the impacts of climate change on hy...Five General Circulation Model(GCM) climate projections under the RCP8.5 emission scenario were used to drive the Variable Infiltration Capacity(VIC) hydrologic model to investigate the impacts of climate change on hydrologic cycle over continental China in the 21 st century. The bias-corrected climatic variables were generated for the Fifth Assessment Report of the Intergovernmental Panel on Climate Change(IPCC AR5) by the Inter-Sectoral Impact Model Intercomparison Project(ISIMIP). Results showed much larger fractional changes of annual mean Evapotranspiration(ET) per unit warming than the corresponding fractional changes of Precipitation(P) per unit warming across the country, especially for South China, which led to a notable decrease of surface water variability(P-E). Specifically, negative trends for annual mean runoff up to -0.33%/ year and soil moisture trends varying between -0.02% to -0.13%/year were found for most river basins across China. Coincidentally, interannual variability for both runoff and soil moisture exhibited significant positive trends for almost all river basins across China, implying an increase in extremes relative to the mean conditions. Noticeably, the largest positive trends for runoff variability and soil moisture variability, which were up to 0.41%/year and 0.90%/year, both occurred in Southwest China. In addition to the regional contrast, intra-seasonal variation was also large for the runoff mean and runoff variability changes, but small for the soil moisture mean and variability changes. Our results suggest that future climate change could further exacerbate existing water-related risks(e.g., floods and droughts) across China as indicated by the marked decrease of surface water amounts combined with a steady increase of interannual variability throughout the 21 st century. This study highlights the regional contrast and intra-seasonal variations for the projected hydrologic changes and could provide a multi-scale guidance for assessing effective adaptation strategies for China on a river basin, regional, or as a whole.展开更多
Changes in monsoon precipitation have profound social and economic impacts as more than two-thirds of the world’s population lives in monsoon regions.Observations show a significant reduction in global land monsoon p...Changes in monsoon precipitation have profound social and economic impacts as more than two-thirds of the world’s population lives in monsoon regions.Observations show a significant reduction in global land monsoon precipitation during the second half of the 20 th century.Understanding the cause of this change,especially possible anthropogenic origins,is important.Here,we compare observed changes in global land monsoon precipitation during 1948–2005 with those simulated by 5 global climate models participating in the Coupled Model Inter-comparison Project-phase 5(CMIP5)under different external forcings.We show that the observed drying trend is consistent with the model simulated response to anthropogenic forcing and to anthropogenic aerosol forcing in particular.We apply the optimal fingerprinting method to quantify anthropogenic influences on precipitation and find that anthropogenic aerosols may have contributed to 102%(62–144%for the 5–95%confidence interval)of the observed decrease in global land monsoon precipitation.A moisture budget analysis indicates that the reduction in precipitation results from reduced vertical moisture advection in response to aerosol forcing.Since much of the monsoon regions,such as India and China,have been experiencing rapid developments with increasing aerosol emissions in the past decedes,our results imply a further reduction in monsoon precipitation in these regions in the future if effective mitigations to reduce aerosol emissions are not deployed.The observed decline of aerosol emission in China since 2006 helps to alleviate the reducing trend of monsoon precipiptaion.展开更多
Long-term observational data indicated a decreasing trend for the amount of autumn precipitation(i.e. 54.3 mm per decade) over Mid-Eastern China, especially after the 1980s(~ 5.6% per decade). To examine the cause of ...Long-term observational data indicated a decreasing trend for the amount of autumn precipitation(i.e. 54.3 mm per decade) over Mid-Eastern China, especially after the 1980s(~ 5.6% per decade). To examine the cause of the decreasing trend, the mechanisms associated with the change of autumn precipitation were investigated from the perspective of water vapor transportation, atmospheric stability and cloud microphysics. Results show that the decrease of convective available potential energy(i.e. 12.81 J kg-1/ decade) and change of cloud microphysics, which were closely related to the increase of aerosol loading during the past twenty years, were the two primary factors responsible for the decrease of autumn precipitation. Our results showed that increased aerosol could enhance the atmospheric stability thus weaken the convection. Meanwhile, more aerosols also led to a significant decline of raindrop concentration and to a delay of raindrop formation because of smaller size of cloud droplets. Thus, increased aerosols produced by air pollution could be one of the major reasons for the decrease of autumn precipitation. Furthermore, we found that the aerosol effects on precipitation in autumn was more significant than in other seasons, partly due to relatively more stable synoptic systems in autumn. The impact of large-scale circulation dominant in autumn and the dynamic influence on precipitation was more important than the thermodynamic activity.展开更多
Under external heating forcing in the Southern Ocean,climate models project anomalous northward atmosphere heat transport(AHT)across the equator,accompanied by a southward shift of the intertropical convergence zone(I...Under external heating forcing in the Southern Ocean,climate models project anomalous northward atmosphere heat transport(AHT)across the equator,accompanied by a southward shift of the intertropical convergence zone(ITCZ).Comparison between a fully coupled and a slab ocean model shows that the inclusion of active ocean dynamics tends to partition the cross-equatorial energy transport and significantly reduce the ITCZ shift response by a factor of 10,a finding which supports previous studies.To understand how ocean dynamics damps the ITCZ’s response to an imposed thermal heating in the Southern Ocean,we examine the ocean heat transport(OHT)and ocean circulation responses in a set of fully coupled experiments.Results show that both the Indo-Pacific and the Atlantic contribute to transport energy across the equator mainly through its Eulerian-mean component.However,different from previous studies that linked the changes in OHT to the changes in the wind-driven subtropical cells or the Atlantic meridional overturning circulation(AMOC),our results show that the cross-equatorial OHT anomaly is due to a broad clockwise overturning circulation anomaly below the subtropical cells(approximately bounded by the 5°C to 20°C isotherms and 50°S to 10°N).Further elimination of the wind-driven component,conducted by prescribing the climatological wind stress in the Southern Ocean heat perturbation experiments,leads to little change in OHT,suggesting that the OHT response is predominantly thermohaline-driven by air-sea thermal interactions.展开更多
中国提出2030年碳达峰与2060年碳中和目标.在达到碳中和的路径下,得益于清洁空气政策气溶胶排放都将显著降低,这可能会对未来气候产生重要影响.本文利用气候模型结合中国本地化的未来排放情景,发现在达到2060年碳中和的过程中气溶胶减...中国提出2030年碳达峰与2060年碳中和目标.在达到碳中和的路径下,得益于清洁空气政策气溶胶排放都将显著降低,这可能会对未来气候产生重要影响.本文利用气候模型结合中国本地化的未来排放情景,发现在达到2060年碳中和的过程中气溶胶减少将在东亚造成0.63 Wm^(-2)的有效辐射强迫以及0.2K的地表增温.最大增温出现在中国东部,为0.5K.同时,华南地区降水将增加(>0.3 mm d^(-1)).尽管碳中和背景下温室气体的减少将有利于缓解气候变化,但是未来清洁空气行动致使气溶胶排放的减少将部分抵消二氧化碳减排带来的气候制冷效应.该研究进一步发现虽然黑碳气溶胶只占中国气溶胶的很少一部分,但降低黑碳排放可能同时有益于空气质量改善并缓解气候变化,达到减污降碳协同增效.展开更多
East Asian dust(EAD) exerts considerable impacts on the energy balance and climate/climate change of the earth system through its influence on solar and terrestrial radiation, cloud properties, and precipitation eff...East Asian dust(EAD) exerts considerable impacts on the energy balance and climate/climate change of the earth system through its influence on solar and terrestrial radiation, cloud properties, and precipitation efficiency. Providing an accurate description of the life cycle and climate effects of EAD is therefore critical to better understanding of climate change and socioeconomic development in East Asia and even worldwide. Dust modeling has undergone substantial development since the late 1990 s, associated with improved understanding of the role of EAD in the earth system. Here, we review the achievements and progress made in recent decades in terms of dust modeling research,including dust emissions, long-range transport, radiative forcing(RF), and climate effects of dust particles over East Asia. Numerous efforts in dust/EAD modeling have been directed towards furnishing more sophisticated physical and chemical processes into the models on higher spatial resolutions. Meanwhile, more systematic observations and more advanced retrieval methods for instruments that address EAD related science issues have made it possible to evaluate model results and quantify the role of EAD in the earth system, and to further reduce the uncertainties in EAD simulations. Though much progress has been made, large discrepancies and knowledge gaps still exist among EAD simulations. The deficiencies and limitations that pertain to the performance of the EAD simulations referred to in the present study are also discussed.展开更多
In this study,the mechanisms underlying the decadal variability of late spring precipitation in South China are investigated by using the latest Community Earth System Model version 1 (CESM1).We aim to unravel the e...In this study,the mechanisms underlying the decadal variability of late spring precipitation in South China are investigated by using the latest Community Earth System Model version 1 (CESM1).We aim to unravel the effects of different climate forcing agents such as aerosols and greenhouse gases (GHGs) on the decadal variation of precipitation,based on transient experiments from pre-industry (for year 1850) to present-day (for year 2000).Our results reveal that:(1) CESM1 can reproduce the climatological features of atmospheric circulation and precipitation for the late spring in South China; (2) only simulations including the forcing of anthropogenic aerosols can reproduce the observed decreasing trend of late spring precipitation from 1950-2000 in South China; (3) aerosols affect the decadal change of precipitation mainly by altering the large-scale atmospheric circulation,and to a less extent by increasing the lower-tropospheric stability to inhibit the convective precipitation; and (4) in comparison,other climate forcing agents such as GHGs have much smaller effects on the decadal change of spring precipitation in South China.展开更多
基金supported by the U.S.Department of Energy, Office of Science, Biological and Environmental Research, as part of the Earth System Modeling ProgramThe NASA Modeling, Analysis, and Prediction (MAP) Program by the Science Mission Directorate at NASA Headquarters supported the work contributed by Teppei J.YASUNARI and William K.M.LAU+2 种基金The NASA GEOS-5 simulation was implemented in the system for NASA Center for Climate Simulation (NCCS).M.G.Flanner was partially supported by NSF 1253154support from the China Scholarship FundThe Pacific Northwest National Laboratory is operated for DOE by Battelle Memorial Institute under contract DE-AC06-76RLO1830
文摘Light absorbing particles(LAP, e.g., black carbon, brown carbon, and dust) influence water and energy budgets of the atmosphere and snowpack in multiple ways. In addition to their effects associated with atmospheric heating by absorption of solar radiation and interactions with clouds, LAP in snow on land and ice can reduce the surface reflectance(a.k.a., surface darkening), which is likely to accelerate the snow aging process and further reduces snow albedo and increases the speed of snowpack melt. LAP in snow and ice(LAPSI) has been identified as one of major forcings affecting climate change, e.g.in the fourth and fifth assessment reports of IPCC. However, the uncertainty level in quantifying this effect remains very high. In this review paper, we document various technical methods of measuring LAPSI and review the progress made in measuring the LAPSI in Arctic, Tibetan Plateau and other mid-latitude regions. We also report the progress in modeling the mass concentrations, albedo reduction, radiative forcing, and climatic and hydrological impact of LAPSI at global and regional scales. Finally we identify some research needs for reducing the uncertainties in the impact of LAPSI on global and regional climate and the hydrological cycle.
基金Supported by the National Natural Science Foundation of China(No.41972244)partially supported by the Science and Technology Basic Resources Survey of the Ministry of Science and Technology(No.2018FY100201)+3 种基金the National Key Research and Development Program(No.2019YFC1407900)to Siyu GOUShuai ZHANGWenyu GANand Tianjiu JIANG。
文摘Paralytic shellfi sh poisoning(PSP)microalgae,as one of the harmful algal blooms,causes great damage to the of fshore fi shery,marine culture,and marine ecological environment.At present,there is no technique for real-time accurate identifi cation of toxic microalgae,by combining three-dimensional fluorescence with machine learning(ML)and deep learning(DL),we developed methods to classify the PSP and non-PSP microalgae.The average classifi cation accuracies of these two methods for microalgae are above 90%,and the accuracies for discriminating 12 microalgae species in PSP and non-PSP microalgae are above 94%.When the emission wavelength is 650-690 nm,the fl uorescence characteristics bands(excitation wavelength)occur dif ferently at 410-480 nm and 500-560 nm for PSP and non-PSP microalgae,respectively.The identification accuracies of ML models(support vector machine(SVM),and k-nearest neighbor rule(k-NN)),and DL model(convolutional neural network(CNN))to PSP microalgae are 96.25%,96.36%,and 95.88%respectively,indicating that ML and DL are suitable for the classifi cation of toxic microalgae.
基金supported by the National Natural Science Foundation of China(Grant No.41171031)National Basic Research Program of China(Grant No.2012CB955403)+3 种基金Hundred Talents Program of the Chinese Academy of Sciences conducted under the framework of ISI-MIPThe ISIMIP Fast Track Project was funded by the German Federal Ministry of Education and Research(BMBF)(Grant No.01LS1201A)supported by Office of Science of the U.S.Department of Energy through the Regional and Global Climate Modeling ProgramPNNL is operated for the US DOE by Battelle Memorial Institute(Grant No.DE-AC05-76RL01830)
文摘Five General Circulation Model(GCM) climate projections under the RCP8.5 emission scenario were used to drive the Variable Infiltration Capacity(VIC) hydrologic model to investigate the impacts of climate change on hydrologic cycle over continental China in the 21 st century. The bias-corrected climatic variables were generated for the Fifth Assessment Report of the Intergovernmental Panel on Climate Change(IPCC AR5) by the Inter-Sectoral Impact Model Intercomparison Project(ISIMIP). Results showed much larger fractional changes of annual mean Evapotranspiration(ET) per unit warming than the corresponding fractional changes of Precipitation(P) per unit warming across the country, especially for South China, which led to a notable decrease of surface water variability(P-E). Specifically, negative trends for annual mean runoff up to -0.33%/ year and soil moisture trends varying between -0.02% to -0.13%/year were found for most river basins across China. Coincidentally, interannual variability for both runoff and soil moisture exhibited significant positive trends for almost all river basins across China, implying an increase in extremes relative to the mean conditions. Noticeably, the largest positive trends for runoff variability and soil moisture variability, which were up to 0.41%/year and 0.90%/year, both occurred in Southwest China. In addition to the regional contrast, intra-seasonal variation was also large for the runoff mean and runoff variability changes, but small for the soil moisture mean and variability changes. Our results suggest that future climate change could further exacerbate existing water-related risks(e.g., floods and droughts) across China as indicated by the marked decrease of surface water amounts combined with a steady increase of interannual variability throughout the 21 st century. This study highlights the regional contrast and intra-seasonal variations for the projected hydrologic changes and could provide a multi-scale guidance for assessing effective adaptation strategies for China on a river basin, regional, or as a whole.
基金supported as part of the Energy Exascale Earth System Model(E3SM)project,funded by the U.S.Department of Energy,Office of Science,Office of Biological and Environmental Researchsupported by the CAS Strategic Priority Research Program(Grant No.XDA20060102)+1 种基金China MOST Program(Grant No.2018YFC1507701)the National Natural Science Foundation of China(Grant No.41775091)。
文摘Changes in monsoon precipitation have profound social and economic impacts as more than two-thirds of the world’s population lives in monsoon regions.Observations show a significant reduction in global land monsoon precipitation during the second half of the 20 th century.Understanding the cause of this change,especially possible anthropogenic origins,is important.Here,we compare observed changes in global land monsoon precipitation during 1948–2005 with those simulated by 5 global climate models participating in the Coupled Model Inter-comparison Project-phase 5(CMIP5)under different external forcings.We show that the observed drying trend is consistent with the model simulated response to anthropogenic forcing and to anthropogenic aerosol forcing in particular.We apply the optimal fingerprinting method to quantify anthropogenic influences on precipitation and find that anthropogenic aerosols may have contributed to 102%(62–144%for the 5–95%confidence interval)of the observed decrease in global land monsoon precipitation.A moisture budget analysis indicates that the reduction in precipitation results from reduced vertical moisture advection in response to aerosol forcing.Since much of the monsoon regions,such as India and China,have been experiencing rapid developments with increasing aerosol emissions in the past decedes,our results imply a further reduction in monsoon precipitation in these regions in the future if effective mitigations to reduce aerosol emissions are not deployed.The observed decline of aerosol emission in China since 2006 helps to alleviate the reducing trend of monsoon precipiptaion.
基金National Basic Research Program of China(2012CB955301)
文摘Long-term observational data indicated a decreasing trend for the amount of autumn precipitation(i.e. 54.3 mm per decade) over Mid-Eastern China, especially after the 1980s(~ 5.6% per decade). To examine the cause of the decreasing trend, the mechanisms associated with the change of autumn precipitation were investigated from the perspective of water vapor transportation, atmospheric stability and cloud microphysics. Results show that the decrease of convective available potential energy(i.e. 12.81 J kg-1/ decade) and change of cloud microphysics, which were closely related to the increase of aerosol loading during the past twenty years, were the two primary factors responsible for the decrease of autumn precipitation. Our results showed that increased aerosol could enhance the atmospheric stability thus weaken the convection. Meanwhile, more aerosols also led to a significant decline of raindrop concentration and to a delay of raindrop formation because of smaller size of cloud droplets. Thus, increased aerosols produced by air pollution could be one of the major reasons for the decrease of autumn precipitation. Furthermore, we found that the aerosol effects on precipitation in autumn was more significant than in other seasons, partly due to relatively more stable synoptic systems in autumn. The impact of large-scale circulation dominant in autumn and the dynamic influence on precipitation was more important than the thermodynamic activity.
基金This work is supported by the National Key Research and Development Program of China(2018YFA0605702)the National Natural Science Foundation of China(NSFC,41906002,91858210,41976006,and 41776009).
文摘Under external heating forcing in the Southern Ocean,climate models project anomalous northward atmosphere heat transport(AHT)across the equator,accompanied by a southward shift of the intertropical convergence zone(ITCZ).Comparison between a fully coupled and a slab ocean model shows that the inclusion of active ocean dynamics tends to partition the cross-equatorial energy transport and significantly reduce the ITCZ shift response by a factor of 10,a finding which supports previous studies.To understand how ocean dynamics damps the ITCZ’s response to an imposed thermal heating in the Southern Ocean,we examine the ocean heat transport(OHT)and ocean circulation responses in a set of fully coupled experiments.Results show that both the Indo-Pacific and the Atlantic contribute to transport energy across the equator mainly through its Eulerian-mean component.However,different from previous studies that linked the changes in OHT to the changes in the wind-driven subtropical cells or the Atlantic meridional overturning circulation(AMOC),our results show that the cross-equatorial OHT anomaly is due to a broad clockwise overturning circulation anomaly below the subtropical cells(approximately bounded by the 5°C to 20°C isotherms and 50°S to 10°N).Further elimination of the wind-driven component,conducted by prescribing the climatological wind stress in the Southern Ocean heat perturbation experiments,leads to little change in OHT,suggesting that the OHT response is predominantly thermohaline-driven by air-sea thermal interactions.
基金supported by the National Key Research and Development Program of China (2019YFA0606800)Jiangsu Science Fund for Carbon Neutrality (BK20220031)+1 种基金Jiangsu Science Fund for Distinguished Young Scholars (BK20211541)support by the U.S.Department of Energy (DOE),Office of Science,Office of Biological and Environmental Research,as part of the Earth and Environmental System Modeling Program。
文摘中国提出2030年碳达峰与2060年碳中和目标.在达到碳中和的路径下,得益于清洁空气政策气溶胶排放都将显著降低,这可能会对未来气候产生重要影响.本文利用气候模型结合中国本地化的未来排放情景,发现在达到2060年碳中和的过程中气溶胶减少将在东亚造成0.63 Wm^(-2)的有效辐射强迫以及0.2K的地表增温.最大增温出现在中国东部,为0.5K.同时,华南地区降水将增加(>0.3 mm d^(-1)).尽管碳中和背景下温室气体的减少将有利于缓解气候变化,但是未来清洁空气行动致使气溶胶排放的减少将部分抵消二氧化碳减排带来的气候制冷效应.该研究进一步发现虽然黑碳气溶胶只占中国气溶胶的很少一部分,但降低黑碳排放可能同时有益于空气质量改善并缓解气候变化,达到减污降碳协同增效.
基金the National Natural Science Foundation of China(42171306,42001270,and 42201337)for providing support for this current studythe support from the National Youth Talent Support Program of Chinasupported by Coastal Observations,Mechanisms,and Predictions Across Systems and Scales-Great Lakes Modeling(COMPASS-GLM),a multi-institutional project supported by the U.S.Department of Energy,Office of Science,Office of Biological and Environmental Research as part of the Earth and Environmental Systems Modeling program。
基金National Natural Science Foundation of China(41405003 and 41521004)supported by the Office of Science,U.S.Department of Energy(DOE),as part of its Regional and Global Climate Modeling ProgramThe Pacific Northwest National Laboratory is operated for the DOE by the Battelle Memorial Institute under contract DE-AC05-76RL01830
文摘East Asian dust(EAD) exerts considerable impacts on the energy balance and climate/climate change of the earth system through its influence on solar and terrestrial radiation, cloud properties, and precipitation efficiency. Providing an accurate description of the life cycle and climate effects of EAD is therefore critical to better understanding of climate change and socioeconomic development in East Asia and even worldwide. Dust modeling has undergone substantial development since the late 1990 s, associated with improved understanding of the role of EAD in the earth system. Here, we review the achievements and progress made in recent decades in terms of dust modeling research,including dust emissions, long-range transport, radiative forcing(RF), and climate effects of dust particles over East Asia. Numerous efforts in dust/EAD modeling have been directed towards furnishing more sophisticated physical and chemical processes into the models on higher spatial resolutions. Meanwhile, more systematic observations and more advanced retrieval methods for instruments that address EAD related science issues have made it possible to evaluate model results and quantify the role of EAD in the earth system, and to further reduce the uncertainties in EAD simulations. Though much progress has been made, large discrepancies and knowledge gaps still exist among EAD simulations. The deficiencies and limitations that pertain to the performance of the EAD simulations referred to in the present study are also discussed.
基金Supported by the U.S.Department of Energy(DOE),Ofce of Science(BER)Earth System Modeling Program
文摘In this study,the mechanisms underlying the decadal variability of late spring precipitation in South China are investigated by using the latest Community Earth System Model version 1 (CESM1).We aim to unravel the effects of different climate forcing agents such as aerosols and greenhouse gases (GHGs) on the decadal variation of precipitation,based on transient experiments from pre-industry (for year 1850) to present-day (for year 2000).Our results reveal that:(1) CESM1 can reproduce the climatological features of atmospheric circulation and precipitation for the late spring in South China; (2) only simulations including the forcing of anthropogenic aerosols can reproduce the observed decreasing trend of late spring precipitation from 1950-2000 in South China; (3) aerosols affect the decadal change of precipitation mainly by altering the large-scale atmospheric circulation,and to a less extent by increasing the lower-tropospheric stability to inhibit the convective precipitation; and (4) in comparison,other climate forcing agents such as GHGs have much smaller effects on the decadal change of spring precipitation in South China.